Liquid cooling means for electrical apparatus



Oct. l0, 1950 K. K. PALUEv LIQUID COOLING MEANS FOR ELECTRICAL APPARATUSFiled Feb. 15, 1944 Inventor: Konstantin Kpaluev,

His Attorney.

` as oil.

Patented Oct. 10, 1950 LIQUID COOLING MEANS FOR ELECTRICAL APPARATUSKonstantin K. Paluev, Pittsfield, Mass., assignor to General ElectricCompany, a' corporation of New York Application February 15, 1944,Serial No. 522,519 1 Claim. (Cl. 174-15) My invention relates to anelectrical apparatus and to a circulating system for an electricalinduction apparatus.

Heretofore it has been customary to manufacture electrical inductionapparatus such as transformers of the enclosed type having a windingwith suitable cooling ducts within anenclosing casing which is filledwith a dielectric fluid such In order to provide a, cooling arrangementfor the oil a heat exchanger arrangement is connected to the casing sothat the hot oil which passes through the winding ducts may pass throughthe heat exchanger and give up the heat which has been received from thewinding. Such systems have either depended upon the natural circulationeffect due to the difference in temperature between the bottom and topof the transformer casing or an auxiliary pump has been provided forforcing the cooling iiuid through the Winding ducts and through the heatexchanger and back to the winding ducts again.'

It is an object of my invention to provide an electrical inductionapparatus of the above mentioned type with an improved arrangement forcirculating the cooling and dielectric fluid through the apparatus.

A further object of my invention is to provide a fluid immersedelectrical induction apparatus which is thermally efficient inoperation.Y

A still further object of my invention is to provide an electricalapparatus having a loss producing element and a heat exchanger forcooling the dielectric fluid within the apparatus with an improvedarrangement for circulating the dielectric fluid 'through the apparatus.

Further objects and advantages of my invention will become apparent fromthe following description referring to the accompanying drawing, and thefeatures of novelty which characterize my invention will be pointed outwith particularity in the claims annexed to and forming a part of thisspecification.

In the drawing Fig. 1 is a sectional side elevation of an electricalinduction Yapparatus which is provided with an embodiment o f myinvention, and Fig. 2 illustrates a modification of the constructionillustrated in Fig. l.

In the design of electrical induction apparatus such as transformers,windings are provided which have a copper cross section dependent uponthe electrical characteristics of the apparatus. Also, in order to coolthe winding it is conventional to provide ducts between the variouscoils, and when concentric cylindrical windings are used ducts areusually provided between the cylindrical windings. The higher the normaloperating voltage between the coils or concentric windings the widermust the ducts be in order to provide the desirable insulationcharacteristics between the windings so as to prevent electricalfailure.

The design of efficient coolers or heat exchange arrangements to' beused'with transformers, however, is not dependent upon electricalcharacteristics but isv dependent upon thermal phenomena andconsiderations of economy, and it has been lcustomary to employ a fairlylarge number vof cooling tubes in series, and each cooler designrequires a certain optimum velocity of the circulating fluid in thetubes. Thus, it is known that the amount of heat exchange between asurface and a fluid is proportional to fluid velocity. `But the powerrequired for fluid flow increases approximately as the third power ofits velocity, so the optimum velocity is dependent upon thermal as wellas economical considerations, Thus given an area of cross sectionthrough which the cooling oil passes and the optimum velocity to obtaina cooler with the best overallv efficiency, a certain quantity of oilwill flow into the intake manifold of the cooler and be exhausted fromthe output of the cooler.

I have determined, however, that the amount of oil flow through thecooler determined by the characteristics mentioned above may be quitedifferent from the optimum quantity of oil flow through the windingducts, and in conventional transformer constructions since the cooler isconnected in a recirculating system so that the oil flows from thecasing through the cooler and back to the casing, the oil flow throughthis series system may be quite different from the optimum `quantity ofoil flow through either the cooler or` winding ducts. This isparticularly true in the so called directed flow transformers wherebaffles are used kbetween the winding and the outside of the casing sothat all the oil which is` exhausted from the cooler and passes into thetransformer casing must pass through th various winding ducts. y y Inthe arrangements illustrated in the drawing I provide ways ofcirculating the oil or cooling dielectric fluid through the windingducts and at the optimum quantity and velocity for the design of thewinding and through the cooler atthe optimum quantity and velocitydepending upon the cooler construction, and these two optimum values maybe and are usually quite different, particularly in directed flowtransformers.

`lteferring more particularly to Fig. l of the vdicated by the dottedline arrows.

drawing, I have provided an electrical apparatus which includes a corehaving winding legs I and II and with windings I2 and I3 surrounding thewinding legs. The windings illustrated in the drawing are of theconcentric cylindrical type and are provided with ducts for carryingiluid in 'heat exchange relation with the windings. In the constructionillustrated in the drawing it will be seen that two concentric ducts I4are provided which extend axially through the winding I3 and twoconcentric ducts I5 which extend axially through the winding I2, but itis to be understood that any suitable number of ducts may be provided.In order to provide what is called directed flow insulating cylinders I6and I1 are placed around the windings I3 and I2, respectively, and apartition or coil support I8 is placed under the windings and extends tothe cylinders. The partition is provided with suitable openings inregistry with the ducts. The core and coils are placed in a casing andthe cylinders I6 and I1 extend from the bottom 2l of the casing so thatthe cylinders provide a partition arrangement between the windings andthe casing. A suitable dielectric fluid such as oil or gas may be placedin the'casing 20.

In order to provide a convenient arrangement for cooling the dielectriciluid a heat exchanger means 23 is provided which is fluidly connectedto the casing by pipes 24 and 25. The fluid may be forced through thecirculating system by a pump 26 which is operated in any suitable mannersuch as by an electric motor 21. Thus the fluid may be withdrawn fromthe casing 20 through the pipes 24 as is indicated by the arrows, passthrough the heat exchanger and be discharged into the casing through thepipe 25. The pump 26 may have such characteristics as determined by thecooler 23 so that the oil will pass through the cooler at the optimumvelocity and quantity for the particular cooler design. As shown, thepump 26 is of the centrifugal type which is characterized by arelatively high pressure head and a relatively low flow. This isespecially suitable for forcing cooling liquid through a coolingradiator as the latter often has a relatively high hydraulic resistanceand does not require a large ilow of liquid through it in order toobtain optimum cooling.

In order to circulate the dielectric and cooling fluid through thewinding ducts at the optimum velocity and quantity determined by thewinding design, I provide a second pump means 30 which forces the oilfrom the area between the partitions I5 and I1 and the casing 20 intothe bottom of the ducts and so that the oil will pass through thewinding ducts at the optimum velocity and quantity depending upon thearea and characteristics of the winding. This circulation is in- Asshown, pump 30 is of the propeller type which is characterized by arelatively low pressure head and a relatively high ilow. This isespecially suitable for circulating cooling liquid through winding ductsat the optimum rate for cooling. It will therefore be seen that I haveprovided a circulatory system including the ducts and two parallelreturn paths, one return path being between the partition I6 and I1 andthe casting 20 and the second return path being through the cooler, orthe uid may be pumped from the pipe 24 through the cooler and to thecasing at one rate and through the ducts at another rate. Thus, forexample, the flow through the winding ducts may be 4000 gallons perminute while 4 the ilow through the heat exchanger may be 1000 gallonsper minute.

In the construction illustrated in Fig. 2 I have shown a modication ofthe system of Fig. 1 including windings 35 and 3S which have ducts 3 1and 38 respectively. The windings are provided in a casing 40 and a heatexchanger 4I is connected to the casing 40 through pipes 42 and 43. Inorder to force the cooling fluid through the heat exchanger I provide apump 44, similar to pump 26, which may be operated through an electricmotor 45. In order to provide what is called directed ow, a baille 46 isprovided at the bottom of the winding and which extends from the outersurface of the windings to the casing. The baille, however, is providedwith suitable openings which communicate with each one of the ducts.Thus oil below the baille 46 in order to reach the other side of thebaffle must pass through the winding ducts.

In order t0 provide a convenient arrangement for circulating the iluiddielectric within the casing at its optimum velocity and volume, Iprovide a second pump 41, similar to pump 30, which operates in anopening 48 in the baille. The pump 41 may be operated in any suitablemanner and in the construction illustrated in Fig. 2 I provide a turbineimpeller or bladed wheel arrangement 49 which is rotated by the movementof the fluid due to the pump 44. Thus a directing baille 50 is providedwhich communicates with the pipe 43 so that the fluid which isdischarged from the pipe 43 is directed against the impeller 49 causingit to rotate. Thus when the pump 44 is operated iluid will be withdrawnfrom the casing 40 through the pipe 42 as is indicated by the arrows andbe discharged into the casing 40 through the pipe 43. At the same timedue to the rotation of the second pump 41, oil will pass through theopening 48 as indicated by the dotted line arrows and up through thevarious winding ducts 31 and 38. Thus the fluid flow in the windingswill be the sum of the ilows of the pumps. It will be understood thathere again by suitably designing the pump the iluid may be forcedthrough the ducts and through the heat exchanger at predetermined ratesdepending upon the characteristics of the winding and cooler. It will benoted that in the system of Fig. 2 the fluid is exhausted below thebaille so that the uid flowing through the cooler will ilow through theducts, while in Fig. 1 the fluid is exhausted from the pump through thepipe 25 between the baille and casing. Thus in the Fig. 2 constructionif,

: for example, the flow through the winding ducts vis 4000 gallons perminute and that through the heat exchanger is 1000 gallons per minute,

Y the ilow through the opening 48 will be the difierencev or 3000gallons per minute.

Although I have shown and described particular embodiments of myinvention, I do not desire to be limited to the particular embodimentsdescribed, and I intend inthe appended claim to cover all modificationswhich do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

A transformer comprising, in combination, an enclosing tank, a windingassembly therein, a normally vertical duct in said winding assemby, apartition in said tank forming a substantially closed bottom compartmenttherein having a top opening communicating with the bottom end of saidduct, a dielectric cooling liquid substantially filling said tank, acooling radiator outside said tank, a centrifugal pump connected toforce said liquid through said radiator by withdrawing it near the topof said tank and discharging it into said tank near the bottom thereofand outside of said compartment, and a pr/opeller type pump mounted inanother opening in said partition for circulating said liquid throughsaid duct by propelling it from outside said compartment into saidcompartment.

KONSTANTIN K. PALUEV.

REFERENCES CITED The following references are of record in the le ofthis patent:

Number Number 6 UNITED STATES PATENTS Name Date Baxter Dec. 19, 1882Nichols May 25, 1915 Hodtum Mar. 26, 1929 MacLeod May 5, 1931 ClarkeDec. 8, 1931 Knotts et al Aug. 16, 1949 FOREIGN PATENTS Country DateEngland June 29, 1928

